GEBV validation test revisited
Keywords:
genomic evaluations, GEBV, international evaluations, model validationAbstract
The properties of the GEBV test in practice were examined. The single-step GEBVs from a test run with Nordic Red Cattle were used as an example. In addition, results from the January 2012 GEBV test from the Interbull Center were presented.
The sampling variation in the test was illustrated by running 10 independent GEBV tests using subsets of validation bulls. The variation in b1 among independent random samples corresponded well the model based standard errors (SE) of the validation regression coefficient. In addition, the SE estimated using boot strap approach did not differ much from model based SE.
The effect of selective genotyping of the validation bulls was shown clearly to affect the estimate of b1. Selection was based on either deregressed proofs or parent averages of the bulls. In the selection examples considered, the Interbull approach to estimate E[b1] seems to agree well with observed reduction in b1. However, it was illustrated that an estimation of variance-covariance components with a simple bi-variate model with missing GEBVs for non-genotyped animals is robust against culling with respect to DRPs.
The GEBV tests submitted to the Interbull by national evaluation centers showed that the test for b1 can be passed by large and small populations. In cases with a small number of test bulls, the test b1=E[b1] has a low power on detection of biasedness. Therefore the improvement of R2 by GEBV over PA should also be required.
Downloads
Published
Issue
Section
License
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
